Internal thread comparator



Feb. 26, 1957 B. W. SWANSON INTERNAL THREAD COMPARATOR Filed Aug. 27, 1953 IN VEN TOR. BR OR WALTER 6 WANJON .foverlong periods of use.

United States Patcnt t INTERNAL THREAD COMPARATOR Bror Walter Swanson, New Britain, Conn., assignor to The Whitney Chain Company, Hartford, Conn, a corporation of Connecticut Application August 27, 1953, Serial No. 376,870

8 Claims. (Cl. 33-199) The present invention relates to comparators for gaging internal threads of a testpiece or the like and has for its principal object to provide a comparator which is not only accurate but also convenient and easy to use, and is particularly suitable for rapidly inspecting successive parts.

Another object is to provide a comparator which is adapted for carrying in the hand of the user, and can be actuated by a simple finger movement for insertion in and withdrawal from successive workpieces without wear on the work contacting elements.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordinglyconsists in the features of construction, combination of elements and arrangement of parts which will'be exemplified in the construction hereafter set forth and the scope of the application of which will be indicated in the appended claims.

In the drawing: 1

Fig. 1 is a front view of a comparator constructed in accordance with the present invention partially sectionalized to show the arrangement of certain of the internal parts thereof;

- i Fig. 2 is a side view of the structure shown in Fig. 1; and v Fig. 3 is a plan view of -one of the gaging elements. Referring to the drawing, a thread. gaging comparator constructed in accordance with the present invention includes a body or casing 2 which is preferably constructed in two halves which are secured together such as by bolts 4. The body or casing 2 is provided with a hand grip 6 of the pistol grip type and an adjacent trigger 3 pivotally supported on the body by means of a pin it).

The body or casing 2 is provided with a vertical cylindrical through bore 12 and a transverse opening 13 communicating therewith for receivingand supporting a pair of jaws 14 and 16, the jaw 14 being a vertically movable jaw and the jaw 16 being a stationary jaw. The jaw 14 is L-shaped in cross section, and comprises a generally semi-cylindrical gage supporting leg it; extending outwardly through the opening 13 and a cylindrical vertical supporting leg 20 at right angles thereto disposed in 'the upper end of the through bore 12. The purpose of the cylindrical supporting leg 2% is to support the jaw for vertical sliding movement but at the same time prevent any cooking movement of the jaw which would cause inaccuracies in the gaging. While accuracy is essential, it also'is essential that the jaw shall be as freely movable in a vertical direction as possible compatible with accuracy, and this is accomplished in accordance with the invention by making the bore 12 larger than leg 20 and inserting a bearingsleeve 22 dimensioned to closely fit in the bore 12 and a bearing assembly comprising ball bearings Zlpositioned by a cylindrical bearing cage 26. As a result, the jaw 14 is tightly held to avoid inaccuracy, it is freely movable up and down, and it will not be subject to wear which might eventually cause inaccuracy even 2,782,523 Patented F eb. 26, 1957 A link 21 connects movable jaw 14 to one end of trigger 8 to control sliding of movable jaw 14 in the bore 12 responsive to squeezing of the trigger against the hand grip 6.

Secured to the body 2 adjacent the upper end of the bore 12 is a collet 23 in which is supported a dial indicator 30 having a stem 32 which is disposed in coaxial relation with the bore 12 for engagement by the end of the vertical leg 26 of movable jaw 14 to indicate changes of position thereof. A collar 34 surrounding the outer end of collet 28 has an adjusting screw 36 which permits clamping of the dial indicator 30 in the collet 28.

The jaw 16 is somewhat similar in shape to the jaw 13 and comprises a gage supporting leg 44) and an anchoring leg 42 received in the lower end of the bore 12. The fixed and movable jaws are urged apart by a spring 44 contained in coaxial bores 46, 43 in the jaws 14, 16 and retained therein by a threaded plug in leg 42 of fixed jaw 16.

The ease with which the device as so far described may be fabricated and assembled or disassembled will probably be apparent from the foregoing description. All of the parts are simple and can be made accurately by ordinary manufacturing techniques, and with the casing 2 formed in two parts, the assembly into a unitary structure is quickly and easily accomplished.

. In accordance with the invention, the gage supporting legs 18 and 40 are arranged to receive replaceable gage elements and 62 which can be removed or inserted in a simple and easy manner (thereby adapting a single gage for use with a variety of work pieces) While at the same time maintaining absolute rigidity and alignment. To this end, the jaw legs 18 and 40 are bored at 64 and 66, respectively, on a common axis parallel to the direction of movement of the leg 20 in the bore 12. A guide pin 68 is located in the bore 66 and extends into sliding engagement with bore 64. Thus the jaw leg 18 may slide up and down on the pin 63 which provides further protection against any tilting movement of the jaw.

The gage elements 60 and 62 are generally similar in shape and are adapted to engage an internal thread at a diameter thereof. The gage element 60 has a relatively narrow finger or thread segment 7 t which is rounded and threaded at 72 to engage the thread of the workpiece,'and a semi-cylindrical shank 74 adapted to seat in the semicylindrical recess 76 in the jaw leg 18. .The shank 74 has a notch 76 at its inner end which is acurately formed to embrace the pin 68, the pin 68 functioning as an aligning pin. When the gage element 66 is properly seated, it is held in seated position by a screw 78. 'Similarly the gage element 62 is provided with a finger or thread segment it somewhat wider than finger 70, and threaded at 82-for engagement with the threads of the workpiece. The semi-cylindrical shank 84 seats in recess 86 of jaw leg 40 and is notched at 88 to embrace the pin 68. A screw 90 retains the gage element 62 in seated position. Thefacing surfaces 92 and 94 of the gage elements'are preferably formed at an angle as best shown in FigureZ to increase the vertical thickness of the gage elements and thus increase their rigidity. As will be apparent, the gage elements 66 and 62 can be easily and simply replaced at any time without disassembly of the device merely by removing the screws-78 and 90, pulling out the gage elements, inserting a new set to fully seated position and replacing the screws 78 and 90. Because of the construction described, absolute rigidity and alignment of the gage elements are assured.-

- Athread gaging comparator constructed as above described i s particularly'suitable for rapidly gaging a number of workpieces, since itis adapted tobe conveniently held in the hand of the user, and by simplyjsqueezingthe trigger 8 the jaws 14, 16 can be brought together to reduce the spacing of the gage elements 60, 62 for quick insertion thereof into a workpiece to be gage'd. The gaging elements can thus be inserted completely into measuring engagement with the workpiece without the necessity of any screwing motion, and thus all wear on the gaging elements of the comparator due to screwing the gage elements into and out of workpieces is eliminated.

Moreover, the provision of the elongated cylindrical bearing cage 26 and ball bearings 24 therein supporting the movable jaw for accurately aligned and smooth sliding movement therein responsive to light forces on the trigger 8 insures that the comparator may be operated easily and conveniently and with reduced fatigue of the user, in rapidly gaging a large number of pieces. Further the provision of the common aligning pin 68 engaging both the fixed and movable jaws for maintaining alignment thereof during their opening and closing insures that the thread gaging elements 60 and 62 will remain properly aligned for consistent repeatable readings during successive gaging operations.

As many changes could be made in the above construction and many apparently widely difierent embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the acompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the language used in the following claims is intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

I claim as my invention:

1. In an internal thread gaging comparator, a casing formed in two separable sections having a longitudinal bore and a lateral opening communicating with the longitudinal bore, a cylindrical ball bearing assembly seated in one end of the longitudinal bore, a generally L-shaped movable jaw having a gage supporting leg extending outwardly through the lateral opening and a cylindrical supporting leg slidably received in the ball bearing assembly, a fixed jaw having a gage support extending parallel to the gage supporting leg of the movable jaw, a pair of gaging elements adapted to seat on said supporting legs, and detachable means external to the casing for retaining 'the gage elements in seated position.

2. In an internal thread gaging comparator, a casing having a longitudinal bore and a lateral opening com- 'municating therewith, a generally L-shaped movable jaw having a gage supporting leg extending outwardly through the lateral opening and a cylindrical supporting "leg slidably received in the bore, a fixed jaw member extending outwardly through the lateral opening, and a guide pin supported in the fixed jaw member and slidably extending through the gage supporting leg of the movable jaw member, said pin being parallel to the axis of said bore and laterally spaced therefrom.

3. In a thread gaging comparator, a body having a fixed jaw and a movable jaw, ball bearings slidably supporting said movable jaw in said body for movement toward and away from said fixed jaw, manual means controlling the position of said jaws, a common aligning pin engaging both of said jaws and having an axis parallel ;to" the direction of relative movement of said jaws to preserve alignment of said jaws during their relative movement, co-operative gage elementssupported on said jaws, each of said gage elements having a recess slidably embracing said aligning pin to preserve alignment of said gage elements during relative movement thereof with said jaws, and a dial indicator on said body for indicating the spacing of said gage elements.

' 4. In a thread gaging comparator, a body having a fixed jaw and a movable jaw slidably supported opposite said fixed jaw, a hand grip on said body and a movable trigger adjacent said hand. grip, a link connecting said trigger to said movable jaw for closing said jaws responsive to squeezing of said trigger, means forming cylindrical bores in said movable and fixed jaws having a common axis parallel to the direction of movement of said movable body, a common aligning pin supported at one end in one of said bores and slidably received in the other of said bores, co-oper-ative gage elements supported on said jaws, means forming notches in said gage elements slidably receiving said aligning pin to preserve the alignment of said gage elements and jaws during opening and closing of said jaws, and a dial indicator having a stem engaging said movable jaw for indicating the spacing of said gage elements.

5. in a comparator for gaging internal threads, a casing, a fixed jaw extending outwardly from the casing, a movable jaw extending outwardly from the casing parallel to the fixed jaw, means supporting the movable jaw for movement perpendicular to the fixed jaw, a guide pin supported on the fixed jaw perpendicular thereto and slidably received in the movable jaw, means forming a semi-cylindrical recess on each jaw extending outwardly from said pin, a pair of gaging elements of generally semi-cylindrical shape adapted to seat in said recesses, means forming notches at the inner ends of said gaging elements for embracing the guide pin, and detachable means for retaining the gaging elements in seated position.

6. In a thread gaging comparator, a body having a hand grip and a movable trigger, a movable jaw in said body, ball bearings slidably supporting said movable jaw, a fixed jaw in the body opposite said movable jaw, spring means urging said jaws apart, a link connecting said trigger to said movable jaw for closing said jaws responsive to squeezing of said trigger, means forming cylindrical bores in said movable and fixed jaws having a common axis parallel to the direction of movement of said movable jaw, a common aligning pin supported at one end in one of said bores and slidably received in the other of said bores, co-operative gage elements supported on said jaws, means forming notches in said gage element-s slidably receiving said aligning pin to preserve the alignment of said gage elements and jaws during opening and closing of said jaws, and a dial indicator on said body having a stem engaging said movable jaw for indicating the spacing of said gage elements.

7. In a comparator for gaging threads and the like, a body having a cylindrical bore, a pistol grip and a movable trigger on the body, a cylindrical bearing cage in the bore, a movable jaw, ball bearings in the bearing cage spacing said movable jaw from the walls of said bore for slidable movement coaxial therewith, a fixed jaw in the body opposite said movable jaw, spring means urging said jaws apart, a link connecting said slidable jaw to said trigger for closing said jaws responsive to squeezing of 'said trigger against said grip, means forming recesses in said jaws aligned on an axis parallel to the axis of said cylindrical bore, a common aligning pin supported at one end in one of said recesses and slidably received in the other of said recesses, co-operable thread gage elements mounted on said jaws in opposed relation, means forming a notch in each of said gage elements slidably embracing said common aligning pin, and a dial indicator on said body having a stem engaged with said slidable jaw to indicate the spacing of said gage elements.

8. In a comparator for gaging threads and the like, a body having a pistol hand grip and a movable trigger, means forming a cylindrical bore in the body, a cylindrical bearing cage, a movable jaw, ball bearings supported in the bearing cage for slidably supporting the movable jaw in the bore, a fixed jaw in the body opposite said movable jaw, spring means urging said jaws apart, a link connecting said slidable jaw to said trigger for closing said jaws responsive to'squeezing of said trigger References Cited in the file of this patent UNITED STATES PATENTS Frauenthal Apr. 19, 1927 Cornell Jan. 16, 1951 FOREIGN PATENTS Great Britain Nov. 22, 1928 

